Appendix testis (Hydatid of Morgagni)
- Present in >90% of testis, usually at the anterior-superior aspect beneath the epididymis head.
- "Fan-shaped" appendage attached to the tunica vaginalis surrounded by columnar epithelium (image A).
- Torsion may occur due to its pedunculated nature.
- Represents the blind cranial end of Müllerian (paramesonephric) duct remnant.
- Present in >30% of testis, often at the superior aspect of epididymis head (image B) & (image C).
- Cystic structure lined by columnar epithelium and filled with serous fluid (image D).
- Subject to torsion.
- Represents the blind cranial end of the Wolffian (mesonephric) duct remnant.
- Torsion of testicular appendages result to bluish discoloration at the superior aspect of the testicle (blue-dot sign), but present in only 1/5 of patients.